Method of making side-fastener stringers

ABSTRACT

A pair of parallel tapes are simultaneously knit on a warpknitting machine with a connecting filament joining their confronting edges. Each tape is formed by a plurality of warp chains laterally interconnected by laid-in weft filaments which span at least three of the wales formed by the chains. The continuous coupling elements are each connected to one of the confronting edges, and the connecting filament is broken either after or immediately before the attaching operation. This connecting filament can be tensioned to be tighter than either the warp or weft filaments to form openings in the tapes adjacent the edge wale. The stitching can pass through these openings, or the coupling heads of the elements can be pushed therethrough. Cutting of this tensioned filament after attachment of the coupling elements substantially closes the openings and causes the tape edge to fold back over the stitching or coupling-turn bights.

[151 3,685,474 [4 1 Aug. 22, 1972 United States Patent Friihlich et al.

[ METHOD OF MAKING SIDE- FASTENER STRINGERS 112/105 Steingruebner 12/105 Waldes..................l l2/105 X Alfons Frohlich- Marie-Luise Cap- [72] Inventors;

m m m w m a R R P my 3. m WM mm r a u "m S y m m Emu S c am h n m .10. W00 a e n .w 1% M n Oct. 20, 1970 21 App1.No.: 82,325

A pair of parallel tapes are simultaneously knit on a warp-knitting machine with a connecti [22] Filed:

. ng filament joining their confronting edges. Each tape is formed Fore'gn Apphcatlon Pnomy Data by a plurality of warp chains laterally interconnected by laid-in weft filaments which span at least three of April 4, 1970 Germany..'.... ...P 2O 16 152.8

the wales formed by the chains. The continuous [52] US. Cl........................................l12/265, 66/86 [51] Int.

coupling elements are each connected toone of the confronting edges, and the connectin g filament is efore the at- [58] Field of broken either after or immediately b taching operation. This connecting filament can be tensioned to be tighter than either the w arp or weft References Clted filaments to form openings in the tapes adjacent the UNITED STATES PATENTS edge wale. The stitching can pass th rough these openings, or the coupling heads of the elements can be pushed therethrough. Cutting of this tensioned filament after attachment of the coupling elements substantially closes theopening's and causes the tape edge to fold back over the stitching or coupling-turn bights.

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SHEET l 0F 6 Jan-1 ATTORNEY PATENTED M1822 1972 sum 5 OF 6 INVENTORS, FROHLICH M. L. CAEPEL E. STUBIGER mi marl JV ATTORNEY PATENTED AUG 2 2 I972 SHEET 8 BF 6 228E E52; 963 E0:

INVENTORS, FROHLICH M. L. CAPPEL E. STUBIGER ATTORNEY METHOD OF MAKING SIDE-FASTENER STRINGERS FIELD OF THE INVENTION The present invention relates to a method of making a slide-fastener stringer comprising a pair of interengageable coupling elements mounted on a pair of support tapes.

BACKGROUND OF THE INVENTION Such a stringer is almost always produced in two operations: formation of the tapes, and mounting thereon of the elements. The tapes are generally woven on a single loom, a method which is highly expensive due to the low efficiency of a weaving apparatus used to produce a thin band. In addition the same band is then paired with another band to serve as the support tapes, or the band is subdivided and its sections are paired to act as the tapes. In either case the supporttape portions which immediately adjoin each other invariably have different characteristics, such as density, elasticity, and size, since no fabric is identical throughout its entire length.

The coupling element usually is a synthetic-resin coil through which a filler cord passes and which itself is sewn to the confronting edges of the tapes. The stitches strike certain of the warp filaments and cause the tapes to buckle slightly, while they damage and weaken these filaments.

In the commonly assigned copending application Ser. No. 52,377 filed July 2, 1970 by Alfons Frohlich and Karl Rohn and entitled METHOD OF AND AP- PARATUS FOR MAKING SLlDE-FASTENER STRINGERS (now US. Pat. No. 3,633,528) a method is disclosed wherein two coils are fed to a sewing apparatus in an interleaved condition, are separated upstream of the sewing station, and are interleaved together again just downstream of this sewing station, i.e., after being sewn onto respective support tapes.

All of these steps are carried out simultaneously and continuously. In such manner the spacing between adjacent coil turns is carefully maintained constant since these coils are left interleaved up to the last minute possible before sewing, so that the finished slidefastener assembly will not buckle or bow. At the same time the full turn is exposed under the sewing needle so that the sewing operation can be carried out at high speed, for large productivity. Immediately after sewing, the two coils are interleaved again to form a finished slide-fastener stringer.

The two coils, according to another feature of that application, can be separated and then fed through a series of guides which keep the intertum spacing the same by tensioning the two coils to the same extent and/or by making them both travel along paths of identical length.

OBJECTS OF THE INVENTION An object of the present invention is an improved method of making an improved slide-fastener stringer.

Another object is to advance the principles set forth in the above-cited patent application.

Yet another object is to provide a method of making a slide-fastener stringer wherein attachment of the coupling elements to the tapes can be effected simply and surely, while the tapes are perfectly matched in their various characteristics.

SUMMARY OF THE INVENTION The above objects are obtained according to the method of the present invention wherein both tapes are simultaneously warp knit on the same machine, and joined at their confronting edges by a connecting filament. The coupling elements are thereafter fastened to the tapes, while the connecting filament can bebroken immediately upstream or downstream of the connecting station.

The tapes are identical in neighboring sections, to each side of the coupling elements, since they are knit simultaneously and are held together by the removable connecting filament. Feeding of the two tapes to the station where the coupling elements are attached becomes a simple operation since only a single band, in effect, need be guided.

These tapes can be knit on a circular knitting machine, but are preferably made on a flat-bed or Raschel machine. A warp knit having laid-in weft filaments with a long reach (number of wales spanned) is used. This reach is, according to another feature of this invention, at least three wales with four being preferable. Such a knit is extremely rigid in the sense in which this term is commonly used in connection with knit fabric.

In accordance with other features of the present invention the edges of the tapes are reinforced, either by doubling the yarn or using bulk yarn, to make the tapes as thick at the edges as they are in the center, since some of the weft laid-in filaments must be left out adjacent the edges to make neatly selvaged tapes. It is also possible to partly set the one of guide bars in the knitting machine to leave out weft filaments so that the finished tapes are of regular cross-sectional thickness.

Anotherfeature of the invention involves tensioning the connecting filament tighter than the other filaments so that the edge wales of each tape at their confronting edges are pulled (bunched) from the rest of the tape to form a series of openings through the tape. These openings serve to accommodate the stitching that holds the coupling elements to the tape so that this stitching need not pass through and damage other filaments, or the coupling heads of the coils can be simply forced through the openings to anchor the bands; After attachment of the coupling coils by either of these methods the connecting filament is broken so that the openings are allowed to close either around the stitching or around the elements, thereby making a very tight fastening. This method also results in the tapes folding back along this line in the valley between the wales so that either the stitching is fully protected on the one side, or the coupling coil is very firmly held at the bights between its turns.

In our concurrently filed and commonly assigned application Ser. No. 82,327 there is disclosed a slidefastener stringer comprising a pair of elongated warpknit support tapes having confronting longitudinal edges, each tape constituted of a plurality of transversely offset longitudinally extending warp chains and laid-in weft filaments transversely connecting the chains to form a warp-knit foundation, and respective elongated continuous coupling elements interconnectable upon movement of a slider therealong and lying along the confronting edges and secured thereto.

In such a stringer the weft filament is laid in a 4-4/0-A pattern and the warp filament is chained in a O-l/l-O pattern, or a 2-0/0-2 pattern, or a pair of such warp filaments are provided, one chained in a -l/l-0 pattern and the other in a 2-0/0-2 pattern.

The tapes of this stringer are formed with stitching holes for attachment of the coupling elements and its weftfilaments are voluminous textured (bulk) yarn.

That application also discloses a method of making a slide-fastener stringer comprising the steps of forming a plurality of transversely offset longitudinally extending warp chains, laying into these chains a plurality of weft filaments to form a pair of warp-knit foundation tapes, securing an elongated coupling element to the confronting edges of the tapes, and thermally fixing the tapes.

Our commonly filed and assigned application Ser. No. 82,326 discloses a slide-fastener stringer comprising a pair of interengageable coupling elements each having a multiplicity of turns, a pair of warp-knit support. tapes having Wale-forming warp filaments and course-forming weft filaments, and a succession of stitches passing between the turns and through the tapes and securing the elements to the confronting edges of the tapes, said stitches having a stitch length greater than the course width. These stitches pass through the tapes between the wales and the stitch length is an integral multiple of said course width, e.g.,

, equal to twice said course width. The weft filaments are laid in a 44/00 pattern and at least some warp filaments are chained in a 0-1/1-0 pattern while other warp'filaments are chained in a 2-0/0-2 pattem'. The warp filaments are chained in a 2-0/0-2 pattern and the warp and weft filaments are of greater bulk adjacent the edges than remote therefrom. The wales are on one face of the tapes, the other face being smooth and engaging the coupling elements.

DESCRIPTION OF THE DRAWING The above and other objects, features, and advantages of the present invention will become apparent in the following description, reference being made to the accompanying drawing, in which:

FIGS. 1, 2, and 3 show the combined notation for three embodiments of the knit according to the present invention;

FIG. 4A isa diagram showing the guide-bar movement for producing the knits of FIGS. 1 and 3;

FIG. 4B is a diagram showing the threading of a knitting machine for producing the knits of FIGS. 1 and FIGS. 5 and 6 show the combined notation of fourth SPECIFIC DESCRIPTION To fully appreciate the structure of the knits, it is necessary to understand the notation of FIGS. 1-6 and 9.

FIGS. 1, 2, 3, 5, 6, and 9 representstandardtricot point paper notation wherein each dot stands for a needle. The vertical rows of dots symbolize the wales and the horizontal rows symbolize the courses. The lines passing around the dots represent the paths of the guides during knitting and, therefore, the pattern of the yarns carried by these guides. FIG.'4A shows the paths of the individual guides, and FIG. 4B shows which of the guides are threaded for each row of needles.

Thus, for the knits of interest here two types will be seen. The guide bar can move from one space to another during each knitting cycle, i.e., the formation of each course, and then move back during the next raising and lowering of the needles. For example, the figure notation for a guide which moves from space 0 to space 1 during one knitting cycle then back from space l to space 0 during the next cycle is O-l/ l0, with the slash mark separating the two cycles.

The other type of guide movement of interest is that of laying-in. In this case the guides do not move in front of the needles (overlap) but merely shog back and. forth behind the needle hooks between cycles. The.

notation here is similar so that 4-4/0-() is the figure notation for a guide which, as the needles move up and down for one course, stand in space 4, and then moves to space 0 where it remains as the next course is knit. In

other words the first two digits signify the two positions between which the guide reciprocates during one knitting cycle and the second two digits indicate the end positions for the next cycle. After every two cycles the movements are repeated. Since for laying-in the guides do not move during the knitting cycles, but between them, these numbers remain the same to each side of the slash mark.

For a more detailed discussion of the above forms of notation reference can be made to the book Advanced Knitting Principles edited by Charles Reichman (National Knitted Outerwear Association: 1964), chapters 26 and 30.

As seen in FIGS. 1 and 3, a slide-fastener stringer comprises a band 1 constituted by a pair of tapes 7 each carrying a nylon coupling coil 2 (see FIGS. 7and 8). Each tape 7 consists of warp yarns 4 and 5 and weft yarns 6, and thetapes 7 are] interconnected at their confronting edges by a connecting filament 8 (see also our concurrently filed and commonly assignedpatent application Ser. No. 82,323.

The warp yarn 4, as shown in FIG. 4A, is chained by the fourth or front guide bar in a 0-1/1-() pattern, whereas the other warp yarn 5 is chained by one of the middle guide bars in opposition'thereto with a 2-0/0-2 pattern. The weft filament 6 is laid in with a 4-4/0-0 pattern by one of the back guide bars. The finished tapes, this, have wales 3 separated by valleys or troughs 15, and courses 21. FIG. 4B shows that the fourth guide bar is fully set, while the other bars are not, so that two tapes will be selvaged and separate when produced on the same knitting machine as is the case here. The conneeting filament is laid in by the second guide bar in a 2-2/0-0 pattern. The band 1 thus can be subdivided, as will be seen below, into a pair of neat selvaged tapes 7, while the fabric characteristics will automatically be identical all through the same course 21, that is, to both sides of the bands center.

FIG. 1 shows how bulk filaments 6' are used instead of the filaments 6 where these run to the edge of the tapes 7. Instead of simply using a bulky or textured yarn, it is also possible to double-thread the respective guide bar. In this manner the tapes 7 are of regular thickness across their entire width so that handling of them later presents little difficulty.

FIG. 3 is essentially identical to FIG. 1, with common reference numerals referring to common elements, except that an edge wale 9 is also formed by a warp filament 4 reinforced as described above. See our commonly filed and assigned application Ser. No. 82,324 for a discussion of such a thickened edge wale 9.

In FIG. 5 there are shown three tapes 7 all commonly joined together by connecting filaments 8. As will be seen below, the tapes 7 are advantageously knit together in groups of four. This embodiment has, however, reinforced warp filaments 5' at the edges to further thicken the edge wales 9 and the filaments 8 are laid in with a 44/0-0 pattern. Otherwise the tapes 7 of FIG. 5 are identical to those of FIG. 3.

FIG. 2 shows three tapes 7 virtually identical to those of FIG. 5 except that connecting filaments 8' are provided which are knitted or chained in 2-0/0-2 pattern.

FIG. 6 shows another tape 7 wherein only two-thirds of the usual amount of laid-in weft filaments 6 are present, in order to reduce the thickness of the tape 7 toward its center.

Any of the tapes shown in FIGS. 1, 2, 3, 5, and 6 can be used with the apparatus shown in FIG. 7,'which has a supply 23 of two pairs 2a of interleaved coils 2. Each of these two parallel pairs 2a passes between a first pair 24 of guide rollers including a driven roller 24a formed with a coil-receiving circumferential groove 24d and an idler roller 24b, each mounted on a member 24c pivoted at 24f and urged by a spring 24e in the counterclockwise direction to tension the interleaved coils 2. From the first guide-roller arrangement 24 each of the pairs 2a passes through a guide eye 25 mounted on a wire 25a fixed to a pivotal shaft 25b coupled to a potentiometer. Thence thecoils 2 pass over idler rollers 24g formed with grooves 241 and mounted on a fixed plate 24h.

Thereafter the coil pairs 2a pass between a roller assembly comprising a smooth cylindrical idler roller 10a and a longitudinally ridged driven roller 10b formed with circumferential coil-receiving grooves 100 and supported by its drive shaft 10f on lugs 10d of a fixed support l0e.

Four support tapes 7 all joined together by filaments 8 are supplied to the roller assembly 10 over a notched guide 26. Each pair of tapes 7 is juxtaposed with one of the coil pairs 2a and they are all thence fed to a cutter blade 14 which severs the central connecting filament 8. Upstream of this cutter 14 is a sewing station 11 having a vertically reciprocable block 13 mounted on a rod 13a of a sewing assembly 13b and carrying a pair of needles 130 for each coil pair 2a and engageable through the coils 2 to fix them to their respective support tapes 7.

Upstream of the sewing station 11 are a pair doubleended sliders 28 which are fitted with small cutters so that they decouple each pair 2a, cut the filament 8, and then interleave the coils 2 again.

The finished stringers are thence fed to a roller assembly 27 comprising an upper roller 27a formed with a pair of circumferential grooves 27d adapted to receive the interleaved coils 2 and mounted on a downwardly biased fork 27b, and a lower longitudinally ridged cylindrical driven roller 270. This roller 27c has a drive shaft 27e coupled, along with the shafts of rollers 24a and 10b, to a drive motor which is controlled by the above-mentioned potentiometer. This motor is also coupled to the sewing drive unit 13b so that, as the tension between the rollers 24g and the roller assembly 24 increases, the potentiometer regulates the drive motor to decrease the speed of the roller assemblies 24 and 27, as well as that of the sewing unit 13b.

This apparatus produces tow stringers having very exact tolerances. They will have the same amount of elasticity, the same intertum coil spacing, and otherwise virtually identical characteristics. Due to the fact that the two tapes 7 are knit simultaneously and remain together, they match perfectly to each side of the coils 2 in the finished fastener stringer.

FIG. 8 shows how these coils are stitched to the smooth side of the fabric, stitching 16 passing through and lying in the valley 15 next to the edge wale 9. The position of the edge wale 9 shown in dot-dash lines is the one it assumes after breaking of the connecting filament. Thus, this edge wale 9 is turned back to cover the stitching 16 and protect it.

FIGS. 9 and 10 show a pair of tapes 7 which are the same as in FIG. 3, except that the filaments 5 at the confronting edges of these tapes are left out, as is the filament 4 next to the edge filament 4. There is thus formed a pair of tapes 7 each having a relatively wide portion 18 and, adjacent their confronting edges, a relatively narrow portion 19 divided by a longitudinally extending ladder-like zone 17. Every other course in such a tape has a relatively large opening 20 in this zone 17 which is ideal for stitching a coil 2 to the tape edge.

In FIG. 10 there is shown how the coupling heads of a pair of coils 2 can be forced through these holes 20 so that no stitching is needed. Once again, once the connecting filament is cut, the edge 19 will fold back'over the bights between the coil turns.

It is also advantageous to tension the connecting filaments 8 much tighter than any of the other filaments to open up the valley adjacent the edge wale 9 as much as possible. This is the case in FIG. 9,-for example, where a reinforced filament 8 is used. In this manner the stitching for the coil has a wider target zone, or the holes 20 are as big as possible, thereby making attachment of the coils 2 very easy. Once the connecting filament thus tensioned is cut, however, the holes 20 shrink, or the width of the valley adjacent the edge wale 9 decreases, to grip the stitching or the threaded-in coils 2. Such tensioning also increases the tendency for the edge wale to fold over, as described above. It is also possible to attach the coils 2 to the tape edges by means of adhesive or welding. This process can be combined with a thermal-fixing process for making the tapes even more rigid and inelastic.

We claim:

1. A method of making a slide-fastener stringer, comprising the steps of:

simultaneously knitting a pair of parallel fabric tapes joined together at confronting edges during bridged by transverse threads along respective knit courses defining openings between them along the respective space; stitching respective coupling elements having continuous chains of coupling heads along each of said longitudinal edges of said tapes by passing the fastening stitches through said openings; and removing said connecting filament, thereby separating said tapes. w

2. The method defined in claim 1 wherein said tapes are warp-knit by the steps of forming a plurality of Iongitudinally extending Wale-forming warp chains from a plurality of warp filaments, and laying into said chains a plurality of course-forming weft filaments with at least some of said weft filamentsbeing drawn across at least three wales.

3. The method defined in claim 2 wherein said tapes are separated by the step of cutting said filament.

4. The method defined .in claim 3 wherein four such tapes are knitted simultaneously in interconnected relationship with three connecting filaments joining the tapes together, said method further comprisingthe step of cutting the central connecting filament whereupon .coupling elements are secured to the two pairs of tapes remaining joined together. 

1. A method of making a slide-fastener stringer, comprising the steps of: simultaneously knitting a pair of parallel fabric tapes joined together at confronting edges during knitting by a connecting filament bridging at least respective edge-wales knit along the confronting longitudinal edges of the tapes; drawing said edge-wales together to bunch the thread of said edge-wales and increase the space between each edge-wale and an adjoining wale of a respective tape, the said space of each tape being bridged by transverse threads along respective knit courses defining openings between them along the respective space; stitching respective coupling elements having continuous chains of coupling heads along each of said longitudinal edges of said tapes by passing the fastening stitches through said openings; and removing said connecting filament, thereby separating said tapes.
 2. The method defined in claim 1 wherein said tapes are warp-knit by the steps of forming a plurality of longitudinally extending wale-forming warp chains from a plurality of warp filaments, and laying into said chains a plurality of course-forming weft filaments with at least some of said weft filaments being drawn across at least three wales.
 3. The method defined in claim 2 wherein said tapes are separated by the step of cutting said filament.
 4. The method defined in claim 3 wherein four such tapes are knitted simultaneously in interconnected relationship with three connecting filaments joining the tapes together, said method further comprising the step of cutting the central connecting filament whereupon coupling elements are secured to the two pairs of tapes remaining joined together. 